Sonic qualities of SET output tubes?


Can you readily identify a 300B, 2A3, 805, 211, etc., amp’s sound with your eyes closed most of the time?


If so, I’sure would like to hear from you.


Amplifier design and the technology utilized within its confines decides the ‘voice’ or influence it will yield as much or more so than merely the output tubes the designer has chosen to use.


I get that part emphatically. One must hear the amp regardless the type of output tube technology on hand.


And yes, some Pentodes and Tetrodes are used as Triodes but are not indeed triodes by their specific architecture. That’s OK, just focus on their use as Triodes herein, please.


There are however certain tube types, irrespective of vintage which have basic undeniable sonic colors or characteristics, apart from their electrical aspects which keep attracting people to amps which use this or that tube in its output stage.


Some love 211s. some adore 300Bs. Some love EL34s configured to run as Triodes. I have an affinity for the latter. So far anyway. This topic could change my mind.


Has your own experience informed you what this or that output tube’s natural flavor regularly announces itself to be so you can have a reasonable expectation of its general presentation?


What sonic attribute continually attracts you to a particular SET tube design, 300B or some others?


Or, conversely, what is it about the sound that would bring you to covet a 211 amp over a 2A3, for example.


Why as another example, would you pick a 2A3 amp over one using 805s or 300B, 211, etc. or vice versa?


Removing ‘vintages’ and electronic or electrical qualities from the argument, what sonic attributes for the more popular S.E.T. amp output tubes have you determined seem to persist in their particular DNA?


I’m asking for input from those SET tube devotees to lend their experiences and knowledge on the subject of what tube sounds like what irrespective of the SET application, generally speaking.


My goal is to try getting a better feel for which SET Tube amp design, if any, I’d want to pursue and possibly invest heavily into going forward as the soul of a new system.


Tremendous thanks to all!

blindjim
The difference between tubes themselves is not that profound. They are just tubes and they have very similar linearity and bandwidth.

This is not true of output transformers!  Here's the problem- the more power there is, the harder it is to get bandwidth out of the transformer (and in this regard, much moreso than is encountered with push-pull; we sidestepped the whole thing by eliminating the transformer altogether).

So as the output power goes down, the sound of the amp improves. 25 years ago the 211 was king, 20 years ago the 300b was king, by sometime in the early 2000s the 2A3 was king, now we're seeing the type 45, 10 and 71 vying for the title. A traditional 45 is good for about 0.75 watts.

Now as transformer designs have improved (some taking advantage of technology not available in the 1920s and 1930s) its been possible to extend bandwidth in higher power designs. So the result is you're going to get a lot of conflicting anecdotal comments.

The other issue I've not mentioned is how well the tube and the output transformer work together. Some tubes want a 5K load and some output transformers present 4.9K or 5.1 K instead of exactly 5K (which will vary from tube to tube...) so you're going to see variance on that account as well.

So don't expect consistency in the comments to follow.
blindjim,
 
I really can't add much more because atmasphere has covered all related details very well and is spot on.

The only thing you may think about is the correct pairing of a lwr pwr set Amp in your system and have reasonable expectations.

I tended to like the 2a3 the best in the right system but my current setup requires more pwr and isn't a good choice now.

You might list the rest of your system,room size,average volume level and types of music you generally listen to.

Kenny.
Ralph, Thank you for this great post. I enjoy your posts as they are always so informative.